Now I get an error message:

38006:(pid 5108):Could not clear 'DIFFERENTIAL' bitmap in database 'ASL' 
because of error 9002. As a result, the differential or bulk-logged bitmap 
overstates the amount of change that will occur with the next differential or 
log backup. This discrepancy might slow down later differential or log backup 
operations and cause the backup sets to be larger than necessary. Typically, 
the cause of this error is insufficient resources. Investigate the failure and 
resolve the cause. If the error occurred on a data backup, consider .
38006:(pid 5108):A nonrecoverable I/O error occurred on file 
"Legato#c2ff9060-7349-46c2-948a-6cc9ffe4c845:" 995(failed to retrieve text for 
this error. Reason: 15105)..
38006:(pid 5108):BACKUP DATABASE is terminating abnormally..

What does that mean?

Not enough space on the database? The database is appr. 30 GB.

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